1. Field of the Invention
The present invention relates to a disc cartridge, and more particularly to a hub assembly for use in a recording disc cartridge comprising a recording disc rotatably mounted in a cartridge case by the hub assembly attached to the central portion of the recording disc.
2. Prior Art
FIG. 1 shows a recording disc cartridge of the above type, wherein a disc case 1 is formed in a generally hard and flat rectangular shape and a floppy recording disc sheet 6 is enclosed in the disc case 1 rotatably supported by a hub assembly 7, which is formed by a combination of an upper half member 7a and a lower half member 7b (FIG. 7). The disc sheet 6 is securely assembled to the hub assembly 7 by clamping both surfaces of a peripheral edge portion of a central hole 5 of the disc sheet 6 by the respective faces of the upper half member 7a and the lower half member 7b. The faces of the both halves 7a and 7b clamping the disc sheet 6 are referred to as butting faces hereinafter. Each of the upper half member 7a and the lower half member 7b is provided with a spindle receiving hole 12 in the form of a through hole defined at its center and a drive pin receiving hole 13 in the form of a through hole defined in a position eccentric to the center of the hub assembly 7, while the disc sheet 6 is provided with a through hole 16 so as to communicate with the drive pin receiving hole 13 of the hub assembly 7, so that when the disc cartridge is mounted on a disc drive apparatus (not shown), a central spindle and a drive pin both provided in the disc drive apparatus are inserted in the spindle receiving hole 12 and the drive pin receiving hole 13 respectively for rotation of the recording disc 2.
In assembling the disc sheet 6 and the hub assembly 7, the disc sheet 6 is put on the butting face of the lower half member 7b having a boss 8 (FIG. 3) in such a manner that the central hole 5 of the disc sheet 6 is aligned with the spindle receiving hole 12 and the through hole 16 is aligned with the drive pin receiving hole 13 of the lower half member 7b, and in turn the upper half member 7a is placed on the lower half member 7b with the peripheral portion of the central hole 5 of the disc sheet 6 interposed between the respective butting faces of the the upper half member 7a and the lower half member 7b, then both halves 7a and 7b are connected integrally.
However, in the process of assembling of the disc sheet and the both halves, it is difficult to align the through hole 16 with the drive pin receiving hole 13 by merely putting the disc sheet on the hub assembly.